Clients not receiving dchp addresses from server

Question

Our dhcp server (windows 2012) is failing to issues addresses to the pc's. Once the lease has expired on the pc (user goes on holiday for a week) the machine will fail to pick up an ip address on the users return.
The event viewer on the server reads "IP address range of scope is 95 percent full with only 7 IP address available"
I have gone through the dhcp scope of which there are 94 exclusions and i have a further 39 machines which require addresses. 
On a class C subnet i should have far more than 7 addresses available.
Any thoughts as to what might be at fault here.  
This topic first appeared in the Spiceworks Community

Answer 1

Just completed a major network upgrade... So decided it was time to stack some ofmy old switches! Can anyone date some of these things?And some before and after shots: The first one is of a distribution cabinet (2 x 10Gig Fiber link ag. to server room) on the other side of our site, the last two are of the core cabinet in my server room. Will take some more pictures later.